1.0 Field of the Invention
The present invention concerns electronic devices having a man-machine interface for the display of information and/or status and for the receipt of information and/or control. The present invention more particularly concerns man-machine interfaces where cost and physical size constraints limit the display size to a few words or lines, and where, for the same reasons, a full user keyboard is impractical.
2.0 Background of the Invention: Man-Machine Interfaces
The advent and widespread low-cost availability of microprocessors and other powerful digital logic building blocks has given rise to an astonishing array of products exhibiting machine "intelligence". This machine "intelligence" often takes the form of increased flexibility and responsiveness to particular user dictates. The user must make his/her dictates known to the machine through a man-machine interface. The man-machine interface desirably permits detailed user control of the machine.
If a machine is to be flexibly controlled by its user at its user interface then an extensive sequence of commands and/or data must typically be entered by the user into the machine. This information entry must typically be in accordance with rigorous procedures. The required exactitude is difficult to achieve, especially to the extent that the required entries are extensive, complex, or infrequently performed.
The goal of man-machine interface design is to permit effective and efficient communication between man and machine, considering the costs to both.
At one end of the spectrum of common interfaces between men and "intelligent" (meaning variably flexibly controllable) machines is the typical interface to a complex, multi-function, digital watch. This interface is characterized by having a very narrow information transfer bandwidth. The user must make large amounts of data and control information known to the watch through typically but a few pushbutton switches. A problem exists with this interface in that large numbers of people desiring to exercise the full functionality of a complex, multi-function, digital watch cannot effectively do so, or are deterred from doing so.
At the other end of the spectrum of common man-machine interfaces is the personal computer. Information is typically entered into the computer by a keyboard or tablet (mouse). The computer typically displays information, questions, and help messages upon a video monitor. The informational bandwidth of this interface is much wider than the informational bandwidth of the user interface to a digital watch. This wider informational bandwidth is required in order to support the relatively more complex tasks that are commanded and parameterized across the interface.
A notable characteristic of the man-machine interfaces exhibiting a relatively wider informational bandwidth, such as those of personal computers, is that the man can usually elicit prompts, questions, and/or help messages from the machine. This capability of the machine to guide the human in performing necessary procedures to enter information is designed to reduce the burden on the human, and to facilitate necessary communication.
In the middle of the spectrum of common man-machine interfaces exist a variety of relatively rudimentary interfaces which, although elementary, must support the human control and parameterization of machines of considerable functional complexity. Interfaces, and machines, in this middle range include common household appliances like microwave ovens and Video Cassette Recorders (VCR's).
A common strategy for implementing man-machine interfaces in this middle range is to use a large number of switches each of which is assigned to a particular datum, or function. Typically, a small display is controlled by the machine. A proliferation of dedicated switches costs money, and occupies considerable room. Nonetheless, when an appropriate multi-function display area shows at various times either prompts or status, and when additional display area is devoted to printed instructions and catalogs, most users manage to use this type of man-machine interface to good effect.
Sometimes, however, the control panels become crowded with switches. The functions enabled become increasingly arcane. The cross- compatibility between the user interfaces of different products becomes nonexistent, making a user unable to transfer his knowledge and experience from one product to another.
Another problem occurs with man-machine interfaces if the number of switches and/or the size of the display is limited (i.e., the information bandwidth is constricted), or if the complexity of the required control is high. This problem is exemplified by the typical interface to a VCR. A small display presents the VCR status and parameterization. Because the VCR can be set to initiate and to conclude actions, such as recording of television, at many different times, a great number of similarly-appearing time datums are variously multiplexed into the small display. The user tends to lose track of what times he/she has and has not specified, and also of his/her progress in the intricate stepwise procedures for selecting and setting a number of different timed occurrences. The programming is consequently often erroneous. The user's failure to have programmed the VCR as he/she desired or expected typically goes unrecognized until improper results are obtained. At this time recovery is often difficult or impossible.